@familyman the easiest way to run a wider tyre is to switch over to one of the option alloys that 240s had.
Anthony Hyde has
a guide on this, running a 16x7 (e.g. Gemini, Hydra) with a 225 tyre, he says the front is okay but the rear needs an 8mm spacer to avoid scrubbing. I think you'd have a much easier time finding a 15x6.5 wheel.
If you're just trying to resolve the appalling grip you get from a 185, I run 205s on my 244 and I have to work really hard to lose traction.
Here is a handy tool for comparing tyre sizes:
https://tiresize.com/comparison/